1. Field of the Invention
This invention relates to signal recording systems and, more particularly, to a signal recording system using a memory for audio signals.
2. Description of the Related Art
The video signal recording system of this kind has been known and is employed in the so-called camera-integrated type video tape recorder (VTR). So, taking an example of this type VTR, it is explained below.
In the camera-integrated VTR, after the shooting has been done with video images and the sound recorded, a BGM (Background Music) or like sound may be additionally recorded. Of the methods of this purpose, the so-called "after-recording" is well known.
Meanwhile, it is recently proposed to utilize the deep-layer recording method. This recording method is called the "VOS (Video On Sound)".
Since the above after-recording method needs no more explanation, this VOS will be briefly described below.
The VOS is for the photographer, while listening to a music previously recorded in a deep layer of the magnetic recording medium, to take pictures in time to this music. The video signal is recorded in a surface layer of the recording medium.
At first, as shown in FIG. 1, an audio signal is previously recorded in a deep layer a1 of a recording medium a3. In the form of a counterpart to this, another audio signal of the same content is recorded in a linear track a2 in the vicinity of one of the edges of the tape-shaped recording medium a3. And, when shooting, the audio signal recorded in the linear track a2 is reproduced by a fixed head a4, a reproducing circuit a8 and an amplifier a9. Listening to the sound issuing from an output terminal a10 in order to confirm the content of the other audio signal recorded in the deep layer a1, the photographer adjusts the timing of actuation of a camera portion to the sound being output from the terminal a10, so that the camera portion composed of an image sensor a11 and a camera signal processing circuit a12 is operated to take pictures. A switch a13 alternates application of a video signal from the camera portion to recording amplifiers a14 and a15. Rotary heads a6-A an a6-B then record the outputs of these amplifiers a14 and a15, while forming video tracks a7 over the deep-layer tracks a1.
Thus, while hearing the previously recorded BGM, the photographer takes pictures. By this, he is enabled to complete taking pictures in time to the BGM or the like.
However, the above-described after-recording method is to perform the recording of the BGM or the like after the end of shooting. So, for the same tape, the recording has to be done twice. Moreover, besides the camera-integrated type VTR, another apparatus which reproduces the sound has to be employed, and its operation has to be performed in synchronism with the VTR. Therefore, the management is very troublesome.
The above-described VOS method, too, requires likewise twice performance of recording on one and the same tape. Further, the shooting period of time is disadvantageously limited by the length of time of the previously recorded audio signal.
Still another problem is that it is usually impossible to replace the video signal by another one under the condition that the audio signal is left as it is.